Introduction to Philosophy Philosophy 110W Spring 2013 Russell Marcus

Transcription

1 Introduction to Philosophy Philosophy 110W Spring 2013 Russell Marcus Class #10: October 1 Smart, The Tenseless Theory of Time aka the B-Theory Marcus, Introduction to Philosophy, Slide 1

2 The Presentist A-Theory P Zimmerman relied on his intuitions about the importance of the present contrasted with past and future events and objects. Thank goodness that s over. P When some thing or event passes from the present into the past, we ordinarily believe that it disappears. It becomes unreal. We lose it. P Yesterday s breakfast P Next Thursday s dinner P These words Marcus, Introduction to Philosophy, Slide 2

3 Intuition and Philosophy P Appeals to intuition are controversial. P Smart prefers scientific evidence to intuitive evidence. More strongly: the only evidence is scientific evidence. P The most fundamental scientific theories are best understood tenselessly. Mathematics contains no references to time. Physics takes time as a variable, but prefers no particular time. The physical laws are indifferent to the direction of time. P Physical theory makes no reference to the present or the past or the future. P I ll say more about intuition if we have time, later. Marcus, Introduction to Philosophy, Slide 3

4 Tenseless Time P Smart argues that we should prefer a theory of time which is tenseless. P The tenseless and minimally token-reflexive language enables us to see the world, in Spinoza s phrase, sub specie aeternitatis (Smart 101). Marcus, Introduction to Philosophy, Slide 4

5 Three Tensed Sentences 1. Bonnie bopped Bobby at 4pm yesterday. 2. Bonnie is bopping Bobby right now. 3. Bonnie will bop Bobby tomorrow at noon. P Zimmerman: these events have intrinsic temporal properties. P Smart: these events have only relational temporal properties. Marcus, Introduction to Philosophy, Slide 5

6 Reichenbach and the Token-Reflexive Solution TR1. There is a time t such that Bonnie bops Bobby at t and t is earlier than the utterance of 1 (by some measure of temporal distance between 4pm yesterday and the utterance of 1, in arbitrary units). TR2. Bonnie bops Bobby simultaneously with the utterance of 1. TR3. There is a time t, such that Bonnie bops Bobby at t, and t is later than the utterance of 3 (by some measure of temporal distance between the utterance of 3 and noon tomorrow, in arbitrary units). P All references to time are rendered in terms of earlier than, and simultaneous with. We can also invoke later than. P No uses of past, present, or future are required for the characterization of times. Marcus, Introduction to Philosophy, Slide 6

7 Tenseless Verbs P No uses of tenses, other than the present tense, are used by the tenseless theory. P Present-tense verbs are to be understood tenselessly. We are taking a four-dimensional view. The block theory P We need, from a grammatical standpoint, some tenses for our verbs. P We think of them as mere grammatical artifacts. Verbs are grammatically present-tense, but logically tenseless. When we say that two plus two equals four we do not mean that two plus two equals four at the present moment. Nor do we mean that two plus two always equaled four in the past, equals four now, and will always equal four in the future (94-5). Marcus, Introduction to Philosophy, Slide 7

8 The Block Theory P Smart is urging a four-dimensional view. Not to be confused with the A-theorist s growing-block theory. P There is a static block, the entire temporal history of the world, past through future. P We can imagine ourselves peering from apart at that block, describing all that happens within it. P The block theory underlies time-travel fiction. Moving among different portions of the block Marcus, Introduction to Philosophy, Slide 8

9 Token-Reflexiveness: A Problem P Time seems to outrun all possible utterances. P We might want to say meaningful things about the future that are not simultaneous with any utterance. P We can measure temporal distance from a current utterance. P But, we can not say anything about utterances simultaneous with such events. Marcus, Introduction to Philosophy, Slide 9

10 P Three things we might say: SN1: The sun will become a supernova, in the future. SN2: The sun is becoming a supernova, now. SN3: The sun became a supernova, in the past. P On the token reflexive approach we might understand SN1-3 as SNTR1-SNTR3. SNTR1. There is a time t such that the sun becomes a supernova at t and t is later than the utterance of SN1 (by some arbitrary measure of temporal distance). SNTR2. The sun becomes a supernova simultaneously with the utterance of SN2. SNTR3. There is a time t, such that the sun becomes a supernova at t, and t is earlier than the utterance of 3 (by some arbitrary measure of temporal distance). P SNTR.1 is fine. Supernova SN: The sun s becoming a supernova is future, will be present and then will be past. P SNTR.2-3 are false because there are no persons or utterances at the time of or after the supernova. Marcus, Introduction to Philosophy, Slide 10

11 A Solution P We might relativize all temporal claims to some claim, whether an utterance or an instance of a sentence, in the present. P In other words, we stick to measurements like SNTR.1. SNTR1. There is a time t such that the sun becomes a supernova at t and t is later than the utterance of SN1 (by some arbitrary measure of temporal distance). P Smart is not just translating A-theory sentences into B-theory sentences. P Some A-theory sentences will have to be eliminated altogether. P Put aside this problem for the token reflexive theory. Marcus, Introduction to Philosophy, Slide 11

12 The B-Theory and Eliminativism P The central claim of the B-theory is that we can do away with appeals to past, present, and future. P Zimmerman s presentist relies on claims about the exceptional nature of the present moment. Sentences about the past and future are legitimate because past, present, and future refer to intrinsic properties of events in respect of which events change. The A-theorist sees SN as ordinary and obvious. P The B-theorist denies that there is any such exception. The present is just one moment among many. The tenseless theory avoids parochial egocentrism. The B-theorist sees SN as ill-formed or nonsensical. Marcus, Introduction to Philosophy, Slide 12

13 Change and the A-Theory P For the A-theory, objects undergo changes as they become real by moving into the present. They become unreal by moving into the past. Object thus do not endure through time. P Smart believes that this aspect of the presentist view is implausible. A man or stone or star is commonly regarded as a three-dimensional object which nevertheless endures through time. This enduring through time clearly brings a fourth dimension into the matter... (94). Marcus, Introduction to Philosophy, Slide 13

14 Change and the B-Theory P The B-theorist s view of change may not be any more plausible. P Change is ordinarily thought of as an active process. P But, the B-theorist s view of change is static. Our notion of time as flowing, the transitory aspect of time..., is an illusion which prevents us seeing the world as it really is (94). P The B theorist must understand what we ordinarily take to be change as the comparison of different temporal slices of four-dimensional objects. When we think four-dimensionally...we replace the notions of change and staying the same by the notions of the similarity or dissimilarity of time slices of four-dimensional solids (95). P This static notion of change does not appear to be the ordinary notion, but Smart believes that it is better. The inability to translate talk of events changing in respect of pastness, presentness, and futurity into our tenseless language can be taken simply as a proof of the concealed token reflexivity of tenses and of words such as past, present, and future. Marcus, Introduction to Philosophy, Slide 14

15 The Rate of Time P Once we introduce change over time, we can start asking uncomfortable questions about the rate at which time passes. P Can time speed up or slow down? P Such questions, Smart believes, lead to an unintelligible infinite regress. We should need to postulate a hyper-time with reference to which our advance in time could be measured (seconds per hyper-seconds)... Moreover, anyone who thought that time-flow was necessary for time would presumably want to say that hyper-time-flow was necessary for hyper-time. He would therefore be driven to postulate a hyper-hyper-time, and so on without end (97). Marcus, Introduction to Philosophy, Slide 15

16 Taking Stock A-theory vs. B-theory P On the side of Zimmerman and the A-theorist Intuitions about the asymmetry of our access to the present moment and to past and future moments. The thank-goodness-that s-over feeling P On the side of Smart and the B-theorist The laws of physics express the ultimate nature of reality. In contrast, the terms of the A-theory are biased. The concepts of past, present, and future have significance relative only to human thought and utterance and do not apply to the universe as such. They contain a hidden anthropocentricity. So also do tenses. On the other hand, the concepts of earlier, simultaneous, and later are impeccably nonanthropocentric (94). P Every event is now at some time or another, and so the notion of now cannot be that of an objective property in nature which singles out some events from others (96). Marcus, Introduction to Philosophy, Slide 16

17 Translation P Smart urges us to translate away the A-theorists s uses of past, present, and future, by using constructions such as TR1-TR3. P But translations work in two directions. P One could try to reduce the B-relations to A-properties just as easily as we turn sentences referring to A-properties into ones invoking B-relations. P To counter that attempt, Smart introduces his fable of the king. Marcus, Introduction to Philosophy, Slide 17

18 The Fable of the King P In the imagined kingdom, the people recognize three classes of entities, alphas, betas, and gammas. Alphas are numbers less than the king s age. Betas are numbers equal to the king s age. Gammas are numbers greater than the king s age. P Every year, betas become alphas and gammas become betas. When the king turns twenty-six, say, the baseball team (which we would say has 25 members), which was Beta is now alpha. P Alphas, betas, and gammas are taken as primitive terms. P They could define our term number as anything that is either an alpha, a beta, or a gamma. Would this show that the notion of number had anything to do with the age of the king? It has indeed been introduced by reference to notions that have to do with the age of the king, but in such a way that this kingly reference cancels out (98). Marcus, Introduction to Philosophy, Slide 18

19 The Unimportance of Translation P Smart believes that our ability to define the B-terms in by using the A-terms does not show that the A-terms, like the king, have anything to do with the ultimate nature of time. P We must choose the scientific view. P I advocate my way, because it fits our ordinary way of talking much more closely to our scientific way of looking at the world and it avoids unnecessary mystification (99). Marcus, Introduction to Philosophy, Slide 19

20 Temporal Intuitions and Science P Recall that Zimmerman defends the A-theory by relying on our intuitions about the present. P Smart instead focuses on details of the construction of scientific theory. P It looks like we re contrasting philosophical intuition with science. Marcus, Introduction to Philosophy, Slide 20

21 Reflective Equilibrium Theory Evidence Marcus, Introduction to Philosophy, Slide 21

22 Philosophical Evidence P In science, the evidence is supposed to be observational. P In philosophy, the evidence is often intuitive. Many philosophical claims are modal, about necessity and possibility. We have no observational evidence of modality. P Intuitions are often the results of thought experiments. What if there were a sixth sense inaccessible to humans? What if we lived in a cave? What if we melted a piece of wax? What if we moved the universe over three inches or ahead ten minutes? What if there were another world just like ours except...? Marcus, Introduction to Philosophy, Slide 22

23 Philosophers on Intuitions P We do not mean a magical power or inner voice or special glow or any other mysterious quality. When you have an intuition that A, it seems to you that A... a genuine kind of conscious episode. (George Bealer). P The term intuition here is not being used in the sense of Spinoza, Bergson, or Husserl. It does not describe a cognitive act that is somehow superior to sensory perception. Nor, on the other hand, does it refer merely to hunches that are subsequently checkable by sensory perception or by calculation. Nor does this kind of intuition entail introspection, since it may just be implicit in a spoken judgment. Its closest analogue is an intuition of grammatical wellformedness. In short, an intuition that p is here just an immediate and untutored inclination, without evidence or inference, to judge that p (L. Jonathan Cohen). P We will call any judgment an intuitive judgment, or more briefly an intuition, just in case that judgment is not made on the basis of some kind of explicit reasoning process that a person can consciously observe (Alison Gopnik and Eric Schwitzgebel). P The Elephant and the Rider The elephant dwarfs the rider, who will have a hard time getting the elephant to do anything it doesn t want to. Still, one might think that the rider is basically in charge. Yet Haidt points out that the analytic system is a recent - and still somewhat buggy -evolutionary innovation, appended to a basically intuitive brain that previously managed pretty well without it... It s not that intuition is a tool that a rational creature often employs; it s rather, to put it crudely, that reason is a tool that a basically instinctual creature often employs to accomplish certain ends. For the most part, the intuitive system sets the agenda (Haybron). Marcus, Introduction to Philosophy, Slide 23

24 Science and Philosophy P A standard view: science proceeds empirically, from observation philosophy proceeds a priori, from intuitions P But proper scientific method is actually not empirical in the way that the standard view depicts. Marcus, Introduction to Philosophy, Slide 24

25 Galileo s Balls P Aristotle had claimed that a heavier body falls faster than a lighter one (H > L). But... P Consider a system consisting of the two bodies attached by a string. P The rate it falls is S. P Since, the light body falls more slowly than the heavier one, it should act as a drag on the system. So, S < H. P But, since the system is heavier than the single heavy body, it should fall more quickly. So S > H. P That s a contradiction. Marcus, Introduction to Philosophy, Slide 25

26 Evidence P In science, unlike in philosophy, evidence is supposed to be observational. P But, where is the evidence in Galileo s experiment? P Regarding the dropping of a rock on a ship (Galilean relativity): So, you have not made a hundred tests, or even one? And yet you so freely declare it to be certain?... Without experiment, I am sure that the effect will happen as I tell you, because it must happen that way (Galileo, Dialogue Concerning the Two Chief World Systems) Marcus, Introduction to Philosophy, Slide 26

27 Stevin s Chain Which way does the chain fall? Marcus, Introduction to Philosophy, Slide 27

28 Stevin s Solution (1605) P Unquestionably in the assumption from which Stevin starts, that the endless chain does not move, there is contained primarily only a purely instinctive cognition (Mach). Marcus, Introduction to Philosophy, Slide 28

29 Methods P In philosophy, unlike science, our evidence is not even supposed to be observational. P Traditionally, we rely essentially on intuitions, on the results of thought experiments. P This method has lately been derided as armchair philosophy. P In contrast, experimental philosophy is supposed to avoid some of the pitfalls of traditional methods. Marcus, Introduction to Philosophy, Slide 29

30 Business P Papers next Tuesday P Eternal Sunshine next Monday Same Time, Same Space Red Pit, 7pm P (Our third movie will be on a Wednesday.) Marcus, Introduction to Philosophy, Slide 30